Epoxy silicon compounds obtained by reacting an alkenyl compound having an epoxy group with a siloxane compound have been conventionally known to serve as a UV curable resin in the presence of a photocationic polymerization initiator (Patent Document 1). However, these compounds have room for further improvement in terms of leakage current when used in applications such as insulators of electric elements (Patent Document 3).
A technique relating to a curable composition obtained by hydrosilylation of an SiH group-containing siloxane compound that is partially substituted by an epoxy group and a polyene compound has already been known. However, the curable composition does not serve as a photocurable resin, and naturally has not been able to be employed for fine patterning by lithography (Patent Document 2).    Patent Document 1: U.S. Pat. No. 5,037,861    Patent Document 2: Japanese Kokai Publication H06-263989    Patent Document 3: Japanese Kokai Publication 2006-291044